The field of the invention relates generally to gasification systems, and more specifically to a method and system for mixing and injecting feed into a gasifier.
At least some known gasifiers convert a mixture of fuel, air or oxygen, liquid water and/or steam, and/or slag into an output of partially oxidized gas, sometimes referred to as “syngas.” In an integrated gasification combined-cycle (IGCC) power generation system, the syngas is supplied to the combustor of a gas turbine engine, which powers a generator that supplies electrical power to a power grid. Exhaust from the gas turbine engines may be supplied to a heat recovery steam generator that generates steam for driving a steam turbine. Power generated by the steam turbine also drives an electrical generator that provides electrical power to the power grid.
The fuel, air or oxygen, liquid water and/or steam, and/or slag additive are injected into the gasifier from separate sources through a feed injector that couples the feed sources to a feed nozzle. The feed sources traverse the feed injector separately and are joined together in a reaction zone downstream of the nozzle. For the reaction to complete in the short time the feed is in residence in the reaction zone, intimate mixing of the feed components needs to occur. At least some know gasification feed injectors include spraying the feed components at high velocity to encourage atomization, however such methods reduce the reaction time available and tend to inhibit a complete reaction.
Some known dry feed injector designs include multiple ports for solid fuel injection in combination with oxidizer ports. The injector tip is similar to that of a showerhead and the solid+gas fuel mixture is split into small quantities along various flow paths inside the injector. Because of the distribution of the solid into multiple streams, the mixing time for the smaller quantity of fuel is very short. Hence, these injectors provide an almost uniform distribution within short distances from the injector tip. However, questions and concerns remain regarding the distribution of the solid fuel across the multitude of ports.